Elastomeric members have been used with mechanical springs in railway cars. Some patents which disclose such arrangements include U.S. Pat. Nos. 3,924,540; 2,640,536; and 3,361,087. Also, a U.S. Pat. No. 3,211,468, not related to railway cars, discloses a solid elastic cushion over a spring housing.
A problem in many railway systems involving mechanical springs is that the springs have a tendency to vibrate and are subject to sudden surges.
The forces generated by the vibrations in the truck and spring surfaces are transmitted to the car body to add to the general discomfort of the passengers riding the car. These forces generated generally result from vertical and lateral vibrations.